A Blu-ray (registered trademark) Disc (hereinafter also referred to as “BD”) on which information is recorded with high density compared with a Digital Versatile Disc (DVD) and a Compact Disc (CD) is known. Patent Literature 1 discloses an optical pickup device that supports not only DVD and CD but also such a BD.
An Ultra High Definition (UHD) BD, which is a triple-layer structure BD, has been proposed. Such a BD has structure in which an L2 layer is further added to a conventional double-layer structure BD that has an L0 layer and an L1 layer.
In the triple-layer structure BD, improvement in playback performance in the L2 layer (jitter) is desired.